A flattering mouth worketh ruin.
Flattery is defined as “To compliment unduly, or over praise.” To praise someone when praise is due is right. But to praise someone for something they’ve done improperly or for some “talent” that they don’t really have is, to say the least, unkind. In the long term it is to court disaster. Foolishness and unwise actions should be reproved, not praised. Be careful not to flatter.